This invention relates to a lens barrel having, for example, two lens groups that are movable in an optical axis direction.
As a lens barrel, there is known, for example, an interchangeable lens of a camera comprising two actuators that move two lens groups in an optical axis direction, respectively (e.g., the publication of Jpn. Pat. Appln. KOKAI Publication No. 2000-147350). Each of the two actuators is a voice coil motor (VCM) including a coil, a magnet, and a yoke. One of the coil and the magnet of each actuator is attached to a movable member holding the lens group, and the other one of the coil and the magnet is attached to an outer frame.
This interchangeable lens comprises the two actuators arranged in the optical axis direction, and hence, a single yoke can be used to the two actuators. Thus, the number of components can be decreased, assembly can be facilitated, and manufacturing cost can be suppressed.
However, in the case that the yoke forming magnetic circuits of the two actuators is constituted of a single member, when one lens group is moved by one actuator, a magnetic force acts on the other actuator due to mutual induction, which causes the disadvantage that the other lens group is moved. In this case, the magnetic force due to this mutual induction becomes a noise component, whereby the two lens groups cannot accurately be driven and controlled.